Hydraulic indexing and clamping fixtures



I Jan. 28, 1969 H. F. HOHLFELDER, JR., AL 3,424,319

HYDRAULIC INDEXING AND CLAMPING FIXTURES Filed Nov. 9. 1966 Sheet 1 of 7 INVENTORS. flay F Hob/fe/der, Jr. Nicholas P. Darash WM dud fi -w. @1114 THE/f? ATTORNE Y5 1969 H. F. HOHLFELDER, JR., ETAL 3,424,319

HYDRAULIC INDEXING AND CLAMPING FIXTURES 1; Jr. Nicholas P. Dams/7 THE/R A Wok/v5 Y5 m 0 7 T r m o v m m Em mm mm mm wm Sheet Lo E Lam Harvey l-T Hoh/fe/de way. M M 5 a4.

Filed Nov. 9. 1966 Jan. 28, 1969 HOHLFELDER, JR" ET AL 3,424,319

HYDRAULIC INDEXING AND CLAMPING FIXTURES Filed Nov. 9, 1966 INVENTORS.

Har.|/ Nicho BY THE/R A TTORNE YS MM MM 54/44 H. F. HOHLFELDER, JR, ETAL 3 24 319 HYDRAULIC INDEXING AND CLAMPING FIXTURES J an. 28, 1969 Filed Nov. 9, 1966 INVENTORS. Hoh/fe/deg Jr. Nicholas P. Darash F v m w H ;2' m THE/f? A TTOR/VE rs Jan. 28, 1969 F. HOHLFEI-DER FETAL 3,424,319

HYDRAULIC INDEXING AND CLAMPING FIXTURES Filed Nov. 9 1966 Sheet 5 of 7 INVENTORS.

A/icho/as P. Darash 4/444 104" 6 4. THE/l'? ATTORNEYS Harvey E Hoh/fe/de; Jr.

Jan.28,1969

1 [Filed Nov. 9. 1966 424 319 H. F. HOHLFELDER, JR., ETAL HYDRAULIC INDEXING AND CLAMPING FIXTURES Sheet 6 of? INVENTORS.

Harvey F Hah/fe/aer, J1: IV/cho/as P. Dams/7 te/464 M M, 5m THE/R A TTOR/VE Y5 J 23, 19 9 l-g. F. HOHLFELDER, JR. ETI'AL HYDRAULIC INDEXING AND CLAMFING FIXTURES Filed Nov. 9. 1966 INVENTORS.

Harvey E Hoh/fe/der, Jr BY Nicholas P. Darash Sheet 1 of 7 THE/R A TTORNE Y5 United States Patent 3,424,319 HYDRAULIC INDEXING AND CLAMPING FIXTURES 7 Harvey F. Hohlfelder, Jr., Painesville, and Nicholas P.

This invention relates to automatic indexing devices of the type normally associated with metal working machines, such as milling machines, turret lathes, and the like. In particular, the invention relates to a novel hydraulically actuated indexing and clamping fixture useful for locating and holding a workpiece for machining by automatic equipment.

To reduce production time on small items, such as bolts, it has become common practice to provide multi-workholder locating and positioning means on the table of a metal working machine, and adjacent the cutting tool of the machine. The piece to be machined is inserted into a workholder or locating means and indexed or moved to a position suitable for cutting. A second piece to be machined can be inserted in a second workholder during the machining operation on the first piece. Hence, essentially continuous machining operation can be achieved.

' From the foregoing, it is apparent that it is necessary to properly locate the workpiece with respect to the cutting tool and also to clamp it tightly in the workholder to prevent movement of the workpiece during machining. Many present devices use complicated mechanical linkages to do this, which linkages are subject to wear, breakage and which often require physical adjustment by the ma- 8 Claims chine operator.

7 It is quite difficult to accurately locate a workpiece for machining, since required tolerances are often measured in tenths of thousands of inches. Bevel or spur gear driven indexing devices simply cannot hold such tolerances, due to inherent play in a gear train. Nor have we found a Geneva device entirely suitable for continuous indexing. Air operated piston devices, using rack and pinion principles,'are subject to mechanical losses and breakdowns whichlead to interruption of operation, machining inaccuracies, and production inefficiency.

An important feature of our invention is that it can be modified easily to clamp and hold a single workpiece in position at a single work station, or it can be used with.

multi-tool equipment to machine a number of workpieces simultaneously at'a number of independent work stations. Similarly, a mere reversal of the flow of hydraulic fluid in our novel fixtures automatically releases clamping of finished workpieces and indexes material to be worked into proper position for machining. In the figures:

FIG. 1 is a plan view of our novel fixture showing the fixture adjacent the cutters of a dual head milling machine;

FIG..2 is a side view taken along line IIII of FIG. 1;

FIG. 3 is a section taken along line IIIIII of FIG. 1 showing our fixturejn an enlarged scale;

FIG. 4 is a section taken along line IVIV of FIG. 3, but with the plungers omitted;

FIG. 5 is a section taken along line VV of FIG. 3;

FIG. 6 is a section taken along line VI-VI of FIG. 3;

FIG. 7 is a section taken along line VII-VII of FIG. 3;

FIG. 8 is a section taken along "line VIIIVIII of FIG. 3;

FIG. 9 is a section taken along line IX IX of FIG. 3;

FIG. 10 is a left side view of the base showing the grooved annulus;

FIG. 11 is a partial right side view of the annulus shown in FIG. 10;

FIG. 12 is a section taken along the line XII-XII of FIG. 10;

FIG. 13 is an enlarged partial section showing the latching means for indexing our fixture;

FIG. 14 is a partial section showing the indexing latch having overtraveled clockwise 5 from the position of FIG. 13;

FIG. 15 is an isometric detail view of a clamp of a type useful in our fixture for holding a workpiece;

FIG. 16 is a plan view of a clamp lock engageable with the clamp of FIG. 15 for locking a workpiece in the clamp;

FIG. 17 is an elevation view of a plunger used to actuate the clamp lock;

FIG. 18 comprises four views of a workpiece machined in the machine of FIG. 1 showing in Aan unfinished workpiece as inserted in a workholder at position A of FIG. 1;

Ba workpiece after the head is milled at position B of FIG. 1;

C-a workpiece after the bottom is milled at position C of FIG, 1; and

Da side elevation of the workpiece shown in C FIG. 20; and

FIG. 26 is a section taken along line XXVIXXVI of FIG. 24.

The fixture In FIG. 1, we have shown our novel clamping and indexing fixture positioned on the table of a standard dualhead milling machine. In plan view, the fixture comprises a circular indexing plate 10 to which are secured a plurality of radially extending clamps 11 -(also shown in isoinetric in FIG. 20). A workholder portion 12 is included at the outboard end of each clamp 11. For clarity, we have illustrated a simple drilled aperture 13 which is adapted to hold a workpiece during machining. Of course, other workholders, such as internal and external collet type holders can be utilized for certain types of workpieces.

A diagonal slot 14 is cut through each clamp 11 in the workholder portion to provide means for closing the aperture 13. A clamp lock 15 (enlarged in FIG. 16) engageable with the workholder portion 12 is pivotally mounted on the outwardly extending flange 16 of the indexing plate. A lip 17 formed on the clamp lock is adapted to engage the clamp to close it. A leg 18 of the clamp lock is engageable with a plunger 19 (only a portion of which is shown in FIG. 1 and which is shown in its entirety in FIG. 17) mounted in the indexing plate, which plunger is actuated by hydraulic fluid pressure, as will be described hereinafter.

In operation, a workpiece, such as bolt 20, is inserted at position A into the aperture 13 of a clamp 11. The unfinished piece, which is shown enlarged in FIG. 18A,, is only representative of a great number of different types and classes of workpieces which can be machined using our fixture. Fluid under pressure is then introduced at inlet passageway 21 causing'the indexing plate 10 to move counterclockwise (as viewed in FIG. 1). The mechanism for producing this rotational movement will be described later in reference to the Indexing Feature.

When the workpiece reaches position B, it is adjacent one head of a dual head milling machine, shown partially at 22. The head carries aspindle 23 on which are mounted a pair of spaced cutters 24, so located that upon advance of the cutters toward the workpiece at B, the head of the workpiece will be milled as shown in FIG. 18B. Upon continued clockwise rotation of the workpiece to a position C, a cut is made on the foot of the workpiece by a second pair of spaced cutters 25 located on a spindle 26 of a second head 27 of the machine. This second cut, made transversely of the cut taken at position B, is clearly shown in FIG. 18C. The finished workpiece is removed from the workholder at position D, and appears as shown in FIG. 18D. Hence, .a finished workpiece is obtained with each complete cycle of operation. Depending upon the number of available workholder portions, it is apparent that production of completely machined pieces can be stepped up considerably by using our fixture.

During intermittent indexing of the fixture from position A to position D, each clamp 11 is adapted to be actuated hydraulically to hold a workpiece for machining. At positions where no cutting operation is programmed, the clamps may be either in a free or neutral condition. This will be described in further detail below under the paragraphs titled Clamping Feature.

Referring to FIGS. 1-3, the fixture of our invention is supported by a base 28 having an outwardly extending flanged foot portion 29 by which it can be secured to the table of a metal-working machine. The upper portion of the base defines an annulus 30. A horizontally extending wall portion 31 joins the annulus to the lower portion of the base and a vertical wall portion 32 forms the lower portion of the base between the portion 31 and the foot portion 29.

A cap member 33 is secured to the top of the annulus by a plurality of vertical bolts 34. Four parallel inclined passageways 35, 36, 21 and 37 extend through the wall portion 31 from the vertical wall portion 32 toward a central aperture 38 of the annulus 30. Each of the passageways is adapted to be connected to lines for carrying hydraulic fluid into and out of the fixture to a source of hydraulic fluid power (not shown).

A pair of vertical channels 39 and 40 extend upwardly within the wall of the annulus within the bottom of the horizontal wall portion, as shown in FIGURES 49. The lower portion of each channel 39 and communicates with the inner end of one of the inclined passageways 37 and 35, respectively.

The outer surface of the annulus has a plurality of vertically spaced circumferential grooves 41, 42 and 43. Grooves 41 is shown to have two oppositely disposed unconnected portions 44 and 45. Groove 42 is a groove portion spaced below the groove portion 44. Groove 43 extends entirely around the circumference of the outer surface of the annulus.

The upper end of the vertical channel 39 is adapted for communication with a portion of groove 41, such that hydraulic fluid under pressure introduced into inlet passageway 37 is forced into and upwardly through channel 39 and into a groove portion 44; hereinafter this enter fluid flow path is called the pressure side.

Vertical slot 46 along the outer surface of the annulus connects groove portion with groove 43 and vertical flat 47 connects groove 42 with groove 43, more particularly shown in FIGS. 10l2. The purpose of the groove 42 and the flat 47 which connects it to the groove 43 is to equalize the pressure of the fluid in the groove 43 so that during draining of the hydraulic fluid it does not back up in the fixture.

The upper end of the vertical passageway 40 is in communication with a portion of groove 43, such that hydraulic fluid under pressure which enters groove 43 can flow around groove 43 and exit through vertical channel 40 and passageway 35; hereinafter this exhaust fluid flow path is called the drain side.

As shown in FIG. 4, circumferential groove 41 comprises a noncontinuous passage having groove portions 44 and 45. A plurality of radial channels 48 drilled in the indexing plate 10 extend outwardly from the outer wall of the annulus. Enlarged cylindrical openings 49 at the outer end of the channels 48 are adapted to envelope a plunger 19 (not illustrated in FIG. 4) which is movable axially under the influence of hydraulic pressure. The figure shows eight such channels 48, only six of which are in communication with a portion of groove 41. Since no hydraulic fluid can flow in the two channels not in communication, the plungers positioned in the openings 50 and 51 are inoperative and the position is called neutral. Plunger channels P are in channels 48 in communication with a groove 44 on the pressure side; plunger channels D are in'channels 48 in communication with a groove 45 on the drain side.

Clamping feature Each of the clamps 11 can be hydraulically actuated to engage a workpiece 20 at a particular station merely by changing the extent of the grooves 44, 45 such that more or less of the number of available channels 48 are in communication with a portion of the groove 44 at any time. This versatility makes our fixture useful for a large number of applications.

The clamping fixture will best be understood by referring to FIGS. 1, 3, 4, 10, 11 and 12 of the drawings. To clamp a workpiece in a workholder, hydraulic fluid under pressure is forced into into inlet 21 on the pressure side of the fixture and into groove portion 44 of the annulus. Groove portion 44 will be in engagement with some of the available channels 48. Under fluid pressure, those plungers in the channels P in communication with groove portion 44 will move outwardly to engage leg 18 of a clamp lock 15 causing the lock to pivot and force lip 17 tightly against the end of a clamp 11. The force of the lip 17 tends to close the slot 14, decreasing the size of the aperture 13 and squeezing a workpiece 20 therein. A

As pointed out before, the indexing plate 10 rotates with respect to the fixed base 28. As it rotates, certain of the channels 48 move out of communication with groove portion 44 on the pressure side and into communication with groove portion 45 on the opposite side of the annulus, whereupon the hydraulic fluid drains from the channel 48 to the groove portion 45, down through slot 46 to groove 43, then to channel 40, into passageway 35 and passes out of the fixture. The clamping feature thus described is dependent for operation upon the position of the indexing plate 10 with respect to the stationary annulus. Rotational movement of the indexing plate causes a corresponding activation and deactivation of various clamps, the extent of the grooves in the annulus being determined by the positions of the operative work stations. In other words, clamps holding workpieces and positioned adjacent a cutting tool of a metal-working machine will be actuated by hydraulic fluid to effect a clamping action on such workpieces; clamps having workpieces which are not adjacent cutting tools will be held in a neutrial or free condition.

Indexing feature FIGS. 3, 8, and 9 illustrate the mechanism of our invention which comprises our novel means for indexing a workholder from one work station to another. Referring to FIG. 3, a cylindrical impeller shaft 52 extends upwardly into the center of the aperture 38 of the annulus 30 of the fixture. A cylindrical impeller bar 53 extends transversely through a horizontal opening in the foot of the impeller shaft and carries resilient impeller blades 54. A threaded plug 55 closes a vertical bore in the center of the foot of the shaft 52. A pair of circular drive ring covers 56 are disposed about shaft 52, one of the covers being above the impeller blades and one being below the blades. A drive ring 57, to which the covers are secured, spaces the covers from each other and forms a cylindrical opening 58 at the foot of the shaft 52. The ends of the blades 54 abuts walls 59 of the opening 58 to form a seal therebetween during operation of the indexing means as shown in FIG. 9; the edges of the blades abut the inner surfaces of the covers 56 during activation of the impeller to seal against fluid leakage. A handle 60 integral with the drive ring extends radially from a portion of the drive ring and into a space formed by cutting out a section of the base wall portion 32 and its foot portion 29. A link 61 joins the handle of the drive ring to an indexing latch 62.

An indexing ring 63 is rotatably supported on the horizontal portion 31 of the base for rotation about the annulus. An index plate 64 is positioned between the inner periphery of the indexing ring and the outer surface of the annulus. Slots 65 are spaced circumferentially around the outer periphery of the index plate. The index plate 64 is secured to the indexing plate by means of bolts 66 and dowels 67. Hence, any rotation of the index plate will produce a corresponding rotation of the indexing plate.

Motion is transferred from the indexing ring 63 to the indexing plate by a latching means shown in FIG. 8 in alternate positions within a chip guard 68 which is secured to the base at the foot portion 29. The latching means, as more clearly shown in FIGS. 13 and 14, includes the indexing latch 62 which is pivotally mounted on the indexing ring at 69. A projection 70 of the latch 62 is adapted to engage a slot 65 of the index plate to prevent further rotation in a clockwise direction and to couple the index plate with the indexing ring for rotation in a counterclockwise direction. A spring loaded latch plunger 71 mounted in plunger block 72 on the indexing ring by a bolt 73 and dowel 74 forces against and maintains engagement of the projection 70 of the latch and a slot 65 during counterclockwise rotation from a position 1 in FIGURE 8 to a position 2 where the outer end of the plunger 71 strikes a stop bolt 75.

Rotation of the indexing ring 63 by which motion is transferred to the index plate and thus to the indexing plate is accomplished hydraulically through cooperation of a stationary impeller and the drive ring to which the indexing ring is linked. The impeller bar 53, its blades 54 and the impeller shaft 52 are shown in FIG. 3; however, reference to FIGS. 9 and 20-26 is necessary for a complete understanding of its structure and operation.

A pair of vertical channels 76 and 77, extend into the impeller shaft 52, the channels being on opposite sides of the blades 54. Inclined passageway 21 communicates with the upper portion of channel 76 and inclined passageway 36 communicates with the upper portion of channel 77. The bottom of each channel is closed with a threaded plug 78. Passageways 21 and 36 are connected to a source of hydraulic fluid under pressure (not shown).

The shaft 52 extends into the annulus such that the one of the vertical channels is on each side of the stationary impeller blades 54. The lower end of each of the vertical channels thus communicates with a portion of the cylindrical opening 58 in which the impeller bar 53 is disposed.

A pair of wedge-shaped drive segments 79 (shown in FIG. 9) are secured to opposite sides of the inner wall of the drive ring 57. A circular wall 80 on the narrow edge of each segment is free to sweep around the shaft 52 in response to fluid pressure introduced against sides 81 or 82 of each drive segment.

. On each side of the impeller bar are a pair of grooves 83, 84, and 85, 86 respectively. The grooves 83 and 86 are connected by a bore 87 and the grooves 84 and 85 by a bore 88. The bores 87 and 88 lie in spaced horizontal planes through the impeller bar. The grooves 84 and 86 are sufliciently long to extend beyond the Wall 80 of each segment so that fluid introduced into the opening 58 through one of the vertical channels on a side of the impeller bar will be directed under pressure against one of the sides 81 or 82 of a drive segment.

operationally, hydraulic fluid under pressure is introduced through passageway 21 and into channel 76 in communication with a groove, for example 85, in the impeller bar. The fluid flows therefrom into the opening 58 and against side 81 of the drive segment on the same side of the impeller blades as grooves 85 and also through the bore 88 into groove 84 in communication with opening 58 on the opposite side of the impeller bar and against side 81 of the other segment. This pressure on the drive segments 79 causes the drive ring to which they are secured to rotate in a clockwise direction carrying with -it the indexing ring to which the drive ring is linked. The indexing latch slides freely out of the slot 65 in the index plate 64 and is also rotated clockwise.

FIG. 13 illustrates the indexing latch in locked position. The indexing latch 62 slides freely out of slot 65 since movement of the drive ring clockwise causes latch 62 to pivot about point 69 thereby lifting projection 70 out of slot 65. FIG. 14 illustrates the position of the latch after the drive ring and handle have moved about 5 clockwise from the locked position.

In the illustrated embodiment the drive ring and latch, which is linked to the drive ring, rotate clockwise approximately 50 under the pressure of the hydraulic fluid introduced in passageway 21 so that the drive ring and latch again move into a position relative to the index plate 64 as shown in FIG. 14, approximately 5 past the slot in the index plate 64 with which it is to engage for indexing movement. At this point, there is a buildup in hydraulic pressure which triggers a microswitch to reverse the flow of hydraulic fluid. The indexing ring reverses under the pressure of the hydraulic fluid which now is introduced against the side 82 of the drive segments and the latch projection is forced into the slot 65 by the latch plunger 71 to secure the indexing ring to the index plate, which in turn is secured to the indexing plate 10 which carries the workholders. Reversal of the drive segments forces the fluid which had been introduced earlier to empty back through the vertical channel 76 to passageway 21 and return to the hydraulic fluid source.

The reversal of the fluid flow causes movement of a workholder carrying a workpiece to be machined from latch position 1, shown in FIG. 8, to a position 2 adjacent a cutting tool. In this operation, the fluid enters passageway 36, travels through channels 77 and enters groove 84 on side 82 of the drive segment 79 causing the segment to be moved in a counterclockwise direction, as viewed in FIG. 9. Fluid also passes out through bore 87 into groove 86 and forces the opposite drive segment to rotate counterclockwise, causing the drive ring, the indexing ring, the index plate and the indexing plate all to rotate in a counterclockwise direction. When the indexing plate, carrying a workholder, reaches the work position 2, the outer end of the plunger abuts the plunger stop holding the workpiece carried in a workholder in a fixed position relative to the cutting tool. Hydraulic fluid under pressure is maintained during machining of the workpiece to keep the workpiece accurately positioned. When the machine operation is completed, the hydraulic fluid flow through the impeller bar is again reversed, the drive segments being driven in the opposite direction (as earlier described) to engage the indexing latch in the next removed clockwise slot 65 for indexing the next succeeding workpiece to a cutting position. This indexing operation continues through a full revolution of the indexing plate to machine a workpiece at each station and can be repeated to provide continuous production.

As pointed out hereinbefore, as a plunger carrying channel 48 on the indexing plate is brought into communication with a portion of groove 44 on the pressure side of the annulus, the clamp operated by that plunger is actuated to secure a workpiece held in the workholder firmly in position for machining. When the indexing plate rotates further to carry the same channel 48 out of communication with the groove portion 44, the hydraulic pressure will be relieved, the clamp loosened and the workpiece free to be removed from the clamp. Thus, we have invented a hydraulically actuated indexing and clamping fixchined. Our novel fixture combines a means for accurately positioning and holding a workpiee for machining and a quick and easy release clamping mechanism for facilitating removal of a completed piece after cutting. A series of production operations can be performed on a single workpiece held in a single workholder or on a number of pieces in a multi-holder device incorporated in our fixture saving labor, changeover time, and without the possibility that tolerances of the finished piece will be exceeded through mistake in locating the workpiece in the holder or with respect to the cutting tool.

While we have described and shown a preferred embodiment of our invention, it is to be understood that it may otherwise be embodied within the scope of the appended claims.

We claim:

1. A fixture for indexing and holding workpieces to be machined by a tool of a metal-working machine, said machine having a fixed table for mounting the fixture, the fixture being connected to a source of hydraulic fluid under pressure, said fixture comprising:

(A) a base member having an upstanding annulus at its upper portion and a lower portion extending from the annulus for securing to the table and including a pair of inlets and outlets for connection to said source;

(B) indexing means having at least one workholder rotatably mounted on said annulus for positioning said workholder adjacent a tool;

(C) driving means connected to an inlet and an outlet and within the lower portion of the base member, said driving means being engageable with said indexing means, and driving the indexing means in response to the magnitude and direction of fluid of pressure introduced to the driving means at the inlet; and

(D) means for clamping a workpiece in said workholder, said clamping means being connected to a second inlet and outlet and operable in response to the position of the driving means relative to the position of the indexing means such that when a workholder carrying a workpiece is adjacent a tool, said clamping means operates to engage the workpiece.

2. The fixture as set forth in claim 1 wherein said indexing means comprises:

(A) an indexing ring supported by the lower portion of said base member and rotatable about said annulus;

(B) a index plate supported by the lower portion of said base member and rotatable about said annulus and within said indexing ring, said index plate having a plurality of circumferentially spaced slots;

(C) latching means pivotally mounted on said indexing ring for engagement with one of said slots of said index plate; and

(D) an indexing plate secured to said index plate and carrying at least one workholder thereon, said indexing ring being rotatable in one direction independent of said index plate by said driving means operating in said one direction, and rotating in engagement with said index plate in the opposite direction when said driving means rotates in said opposite direction.

3. A fixture as set forth in claim 2 wherein said driving means comprises:

(A) a stationary vertical shaft extending upwardly into said annulus and having a pair of spaced vertical channels, one channel being in communication with said first mentioned inlet and one being in communication with said first mentioned outlet;

(B) a circular drive ring having a central aperture therein and within the lower portion of the base member, said drive ring being linked along its periphery to the indexing ring and suspended therefrom for rotation about said vertical shaft;

(C) a cylindrical chamber formed by the aperture in said drive ring and into which said vertical shaft extends, said chamber being connected to said pair of spaced vertical channels;

(D) an impeller bar secured to the shaft and in said chamber, said bar having blades which contact the walls, top, and bottom of the chambers;

(E) a pair of drive ring segments secured to said drive ring and in said chamber, one of said segments being on each side of said blades, whereby upon introduction of fluid under pressure in said chamber on one side of said bar, the drive ring segments rotate within said chamber rotating said drive ring and said indexing ring around said index plate to engage with one of said slots in said index plate, and upon reversal of direction the fluid into said chamber, the drive ring segments rotate in the opposite direction carrying the drive ring, indexing ring, index plate and indexing plate a corresponding distance in said opposite direction.

4. A fixture as set forth in claim 2 wherein the clamping means comprises:

(A) at least one planer non-continuous circumferential channel having two spaced grooves extending around the periphery of said annulus;

(B) a pair of vertical channels on opposite sides of the wall of said annulus l) a portion of one of said vertical channels connected the second inlet to the source of supply of hydraulic fluid;

(2) a second portion of said channel in communication with a groove portion;

(3) a portion of the second vertical channel being in communication with said other groove portion; and

(4) a second portion of the second vertical channel being connected to said second outlet or said source of supply of hydraulic fluid; and

(C) means in communication with said groove portion connected to said inlet to fluid pressure for holding a workpiece to be machined.

5. The fixture as set forth in claim 4 wherein said workpiece holding means comprises: (A) a clamp secured to the extending outwardly from and beyond said indexing plate;

(B) at least one plunger responsive to fluid pressure and being radially mounted on the indexing plate; (C) a radial passageway in the indexing plate in communication with the plunger on one end thereof and adapted for communication with a portion of at least one circumferential groove portion of the annulus on the other end; and (D) locking means pivotally mounted on said indexing 60 plate, one end thereof being adjacent an end of the plunger, the other end thereof being adjacent the clamp, such that when the plunger is actuated by pressure of the fluid entering said radial passageway, the locking means engages the clamp to tighten the workpiece in the workholder, and when said indexing plate rotates to take said radial passageway out of communication with said fluid-carrying circumferential groove portion, said plunger disengages from said clamp and releases said workpiece.

6. A hydraulically operated clamping device having means for selectively clamping one or more workpieces on a rotating plate having a plurality of workholders coniprising:

(A) an annulus about which the plate rotates;

(B) a pair of vertical channels in the annulus, one

channel being adapted to be connected to an inlet of hydraulic fluid and the second channel being adapted to be connected to an outlet ofhydraulic fluid;

(C) a plurality of horizontally disposed grooves on the outer periphery of the annulus, at least two of said grooves being positioned in the same horizontal plane forming a non-continuous passage about the outer periphery of the annulus, one of said grooves being connected to the channel connected to the inlet of hydraulic fluid and another of said grooves being connected to the channel connetced to the outlet of hydraulic fluid;

(D) a plurality of radial passageways in the plate, said passageways being positioned to periodically connect with the two horizontal grooves;

(E) means in each passageway for actuating a clamp whereby hydraulic fluid may be forced into the inlet channel to the groove on the annulus connected with the inlet channel and to the radial passageways in the rotating plate to actuate the clamp associated with the passage way and when the rotating plate has moved so that the radial passage way is connected to the horizontal groove which is connected to the channel connected to the outlet of hydraulic fluid, the fluid flows out releasing the clamp.

7. The clamping device set forth in claim 6 having a third horizontally disposed groove on the outer periphery of the annulus, said groove being positioned ina different horizontal plane from the first two grooves forming the non-continuous passage and a vertical channel connecting the third groove with the horizontal groove connected to the channel connected to the outlet of hydraulic fluid.

8. A hydraulically operated driving means for a fixture in which and indexing plate carrying a plurality of workholders is driven about a central annulus by rotatable movement of an indexing ring linked to a drive ring having a cylindrical chamber, comprising:

(A) a stationary impeller bar positioned in said cylindrical chamber and dividing said chamber into two separate cavities;

(B) a pair of drive ring segments secured to the drive ring, one of said segments being positioned in each of said cavities;

(C) means for introducing hydraulic fluid into said cavities and against the sides of the drive segements whereby the drive ring is rotated causing the indexing plate to rotate.

References Cited UNITED STATES PATENTS 2,352,551 6/1944 Kende et a1 5ll34 X 3,012,454 12/1961 Brodbeck 77-64 3,336,823 8/1967 Bonzi 7764 ANDREW R. JUHASZ, Primary Examiner.

G. WEIDENFELD, Assistant Examiner.

U.S. Cl. X.R. 

1. A FIXTURE FOR INDEXING AND HOLDING WORKPIECES TO BE MACHINED BY A TOOL OF A METAL-WORKING MACHINE, SAID MACHINE HAVING A FIXED TABLE FOR MOUNTING THE FIXTURE, THE FIXTURE BEING CONNECTED TO A SOURCE OF HYDRAULIC FLUID UNDER PRESSURE, SAID FIXTURE COMPRISING: (A) A BASE MEMBER HAVING AN UPSTANDING ANNULUS AT ITS UPPER PORTION AND A LOWER PORTION EXTENDING FROM THE ANNULUS FOR SECURING TO THE TABLE AND INCLUDING PAIR OF INLETS AND OUTLETS FOR CONNECTION TO SAID SOURCE; (B) INDEXING MEANS HAVING AT LEAST ONE WORKHOLDER ROTATABLY MOUNTED ON SAID ANNULUS FOR POSITIONING SAID WORKHOLDER ADJACENT A TOOL; (C) DRIVING MEANS CONNECTED TO AN INLET AND AN OUTLET AND WITHIN THE LOWER PORTION OF THE BASE MEMBER, AND DRIVING MEANS BEING ENGAGEABLE WITH SAID INDEXING MEANS, AND DRIVING THE INDEXING MEANS IN RESPONSE TO THE MAGNITUDE AND DIRECTION OF FLUID OF PRESSURE INTRODUCED TO THE DRIVING MEANS AT THE INLET; AND (D) MEANS FOR CLAMPING A WORKPIECE IN SAID WORKHOLDER, SAID CLAMPING MEANS BEING CONNECTED TO A SECOND INLET AND OUTLET AND OPERABLE IN RESPONSE TO THE POSITION TO THE DRIVING MEANS RELATIVE TO THE POSITION OF THE INDEXING MEANS SUCH THAT WHEN A WORKHOLDER CARRYING A WORKPIECE IS ADJACENT A TOOL, SAID CLAMPING MEANS OPERATES TO ENGAGE THE WORKPIECE. 